1. Field of the Invention
The present invention relates to a lubrication unit for engines, and more particularly to a lubrication unit for engines suitable for mounting on a planing watercraft such as a small planning boat.
2. Description of the Background Art
As seen in FIG. 17 of the present application, an engine employing a lubrication system has been available in the background art. The engine is further described in JP-A-11-93634, the entirety of which is hereby incorporated by reference. The engine 1 is mounted on a small, planing boat 2, and includes an oil feed pump (not shown) for feeding oil in an oil tank 3 provided on the side thereof to the engine 1, a crankcase 4 in which oil used for lubricating each part of the engine is collected, and an oil recovery pump (not shown) for feeding oil from the crankcase 4 to the oil tank 3. An opening 3a is provided on top of the oil tank 3, and the opening 3a is secured by a cap 6 having a dip stick (oil level gauge) 5.
The aforementioned engine 1 is mounted on the small planing boat 2. Since there is only a slight space between an engine bottom 1a and a bottom of the vessel body 2a, one has to remove the aforementioned cap 6, insert a tube for sucking oil from the opening 3a, and drain the oil when changing engine oil. Therefore, the present inventors have determined that the oil in the oil tank 3 can be drained relatively satisfactorily. However, the oil in the crankcase 4 cannot be drained easily and/or satisfactorily with this arrangement of the background art.